Heat seamer



P 1952 J. M. HUMPHREY ETAL 2,611,725

HEAT SEAMER 6 Sheets-Sheet 1 Filed Oct. 1e, 1950 FIG INVENTORS J- M.HUMPHREY BY J. J. GREVICH ATTORNEY Sept. 23, 1952 Filed Oct. 16, 1950 J.M. HUMPHREY EI'AL HEAT YSEAMER FIG- 2 6 Sheets$heet 2 ATTORNEY Sept. 23,1952 J. M. HUMPHREY EIAL 2,611,725

I HEAT SEAMER Filed Oct. 16, 1950 G SheetS-Sheet s FIG- 3 INVENTORS J.M. HUMPHREY J- J. GREVICH ATTORNEY Sept. 23, 1952 J. M. HUMPHREY ETAL2,611,725

HEAT SEAMER Filed Oct. 16, 1950 e Sheets-Sheet 4 FIG- 4 INVENTORS J. M.HUMPHREY BY J. J. GREVICH ATTO RN EY P 1952 J. M. HUMPHREY EI'AL2,611,725

HEAT SEAMER Filed Oct. 16, 1950 6 Sheets-Sheet 6 i Q N g o L:

INVENTORS J- M HUMPHREY J. ,J. GREVICH ATTORNEY patented Sept. 2 3, 19522,611,725 g v f HEAT SEAMER.

James M. Humphrey, New Richmond, Wis., and

John Joseph Grevich, St. Paul, Minn., assignors, by mesne assignments,to Harris Trust and Savings Bank and W. H. Milsted, as trusteesApplication October 16, 1950, Serial No. 190,391

This invention relates to sealing and more particularly to a machine forproviding a seam on thermoplastic articles or for forming a continuoussheet of such material from a plurality of sheets thereof and in whichthe seam may be provided with a binding strip if desired. Thisapplication is a continuation in part of copending application, SerialNo. 715,576, filed Decemberll, 1946 which has resulted in U. S. PatentNo. 2,554,360.

. ..In the forming of seams on thermoplastic materials three mainfactors are involved, these being time, temperature, and pressure. Manyof the sealing machines heretofore utilized provided no means forvarying these factors and consequently were only applicable topredetermined types and weights of material. In certain types of seamsan added factor may be included by applying a solvent to the materialswhich assists informing the seams, and in making this type of scam it isdesirable to control the quantity of solvent utilized. Many of the priorart machines were also cumbersome and were also relatively costly tomanufacture and in many instances required highly skilled operation.

It is a'ccordinglyan object of this invention to provide a simple,inexpensive practical heat seamer of relatively light weight which canbe used to efiiciently and satisfactorily join sheets or bodies with orwithout employing a joining or binding strip at the seam and in whichthe seam will be of the desired strength and of pleasing appearance.

A further object of the invention is to provide a sealing machine whichmay be operated continuously or intermittently much in the manner of aconventional sewing machine in order to provide a seam on thermoplasticarticles or materials.

A further object of the invention is to provide a sealing machine inwhich the rate of feed of articles or materials between the sealingelements may be very closely controlled in order to control the timefactor in the sealing operation.

It is a further object of the invention to provide a sealing machine inwhich the temperature of the sealing elements may be closely controlled,which temperature may also be varied during the operation of the machineand in which means is further provided to accurately control thepressure between the sealing elements.

A still further object of the invention is to provide a sealing machinein which a thermoplastic tape may be longitudinally folded and fed tothe sealing'elements in order to provide a binding for 20 Claims. (01.154-42.-3)' f the seam being "formed and in which means is provided toapply a'solvent to one side' of'theltape and to control the amount ofsolvent applied.

It is a further object of the invention toprovid' a sealing machine inwhich thermoplastic tape to form a" binding for the seam is suppliedfrom a roll andin which means is providedto pull the tapefrom the rolland to renderthis tape-pulling means inoperative when'the tape is notbeing utilized. Y v v It is a further object 'of the inventiontolp'rovide a sealing machine which'm'ay be economi cally constructed ofreadily availablelpar'ts and which may be operated by relativelyunskilled labor.

Further objects and advantages ,of. the. invention will be apparent fromthe following descrip ti'on taken in conjunction with the accompanyingdrawings, wherein:

Fig. 1 is an elevational viewshowing the'front or operators side of thesealing'machi'neof'this invention; f 1..

'Fig. 2, a top plan view of' the sealing machine shown in Fig. 1; I f.Fig.' 3, a fragmentary elevational view'from opposite side, as shown inFig. 1,'withth'e house ings and covers. removed and showing "thearrangement of the'inechanismin the sealing machine of this invention; II

Fig. 4, a fragmentary sectional view on the line 4+4 of Fig.'3andshowing the variableispeed drive for feeding material to the sealingmachine, Fig. '5, a longitudinal sectional view showing one of thesealing elements, the drivemeans therefor, and the means forcontrol1ingthe'temperature of such heating elementsi Fig. 6, afragmentary sectional view onithe line' 5-6 of Fig.5,and showing themeansfor, apply,- ingpressure betweenthe sealing elementsg...

Fig. 7, a sectional view on theline 1+1 of Fig. 2 and showing the meansforapplying solvent to the binding tape and the tape-pulling meansutilized with the machine of this invention?" Fig. 8, a fragmentarysectional view on the line 88 of Fig. 2 and showingthe means forsupplying solvent to the solvent-applying means} Fig. 9, a fragmentarysectional view onthe line 9 9 of Fig. 7 and showing the means for rendering, the tape-puller inoperative during periods in which binding tape isnot utilized; I; i If Fig. 10, a fragmentary sectionalviewshowing themeans forremoving excess solventfrom the tape; '3 'i. U Fig. 11, aschematic circuit diagram on the :Qlfififi switch l5 controlling theheating elements in such rolls, there being three positions in thelatter switch: Off, Hi-heat, and Regular heat;

Secured to the top of frame I0 is a work supporting table I6 which isprovided with a plurality of parallel, spaced, longitudinally extendingslots I'I each of which serves to receive a belt I8 extending throughoutthe length of the table IB ,'these belts serving to receive and conveywork deposited thereon. Belts I8 are received over pulleys I9 at one endthereof, which pulleys are mounted on shaft which in turn is journaledin bearings 2| mounted on the frame I0. The opposite ends of belts I8are received over pulleys 22 mounted on shaft 23 also journaled onbearings secured to the frame I9, shaft 23 being driven by a sprocketmounted thereon, which sprocket serves to receive a chain 24, whichchain in turn'is received over a sprocket 25 mounted on'one of thesealing rolls, the structure of which will be'later described. I

To adequately inspect the work in progress a lamp 26 is provided whichis mounted on a flexible conduit 21 of familiar goose neck type whichpermits adjustment of lamp 26 to any desired position. Conduit 21 ismounted on a portion 28 of the frame I0 and suitable electricalconnections are provided to energize the lamp 26. Ali on and ofi'switch29 may be provided on the lamp socket to conveniently control the same.

The sealing elements of the machine of this invention comprise a pair ofsealing rolls 39 and 3 I 'rotatably mounted one above the other andbetween which the work is adapted to pass. These rolls may be providedwith knurled surfaces or serrations in order to indent the work andprovide a more efficient seal. Roll 30 is fixed to a shaft 32 which inturn is journaled in bearings received in uprights 34 which are securedto the frame I0. Roll 30 also serves to support the sprocket 25 whichdrives chain 24 and the conveyor belts I8. The shaft 32 is providedadjacent the end remote from the roll 30 with a spur gear 35 and asprocket 36. Sprocket 36 serves to receive a drive chain 31 which istrained over a sprocket 38 mounted on a shaft 39 extending from a speedreducer 40. Speed reducer 49 forms a part of and is directly attached toa variable speed drive mechanism M which is supported by cross members42 secured to frame I9 by screw-threaded fastening means or the like 43.Variable speed drive mechanism 4I also is attached to and supports adrive motor 44 of conventional type which is provided with a capacitator45 mounted on the top thereof by a strap 46.

Variable speed drive mechanism is of conventional commercially availableconstruction and includes a top plate 4'! which may be provided withindicia 48 to facilitate adjustment of a control arm 49 which isattached to a control shaft 50 extending within the mechanism 4| arm 49"being split as at 5| to permit convenient ad- 4 justment thereof on theshaft 50. The arm 49 is clamped to shaft 50 by screw-threaded fasteningmeans or the like 52.

The outer end of arm 49 is provided with a slot 53 which serves toslidably receive a pin 54 secured to an arm 55 pivotally mounted at 56on frame i9. Arm 55 is pivoted about its mounting 56 by a cable 51 whichleads over a pulley 58 journaled in bearings 59 mounted on one of thecross members 42, the cable 5! extending downwardly as shown in Fig. lto an arm 60 which is fixed to a shaft 6| journaled in frame IIIadjacent the lower portion thereof. Shaft BI is also provided with atreadle 62 disposed in a position convenient to the operator in order tocontrol the speed of operation of the sealing machine.

Actuation of treadle 62 will, as seen from the drawings, rotate or pivotthe arm 55 about its mounting 56 in a counter-clockwise direction, asseen in Fig. 4, to move the arm 49 and thus actuate the control shaft 50of the variable speed mechanism 4| to rotate the shaft 39 at a speed inaccordance with the movement of the arm 49. With the arm 49 in theposition shown in full lines in Fig. 4 the shaft 39 and elements driventhereby are at rest and with the arm 49 at its extreme position aftermovement in a clockwise direction as shown in dotted lines in Fig. 4,the shaft 39 will be driven at its maximum speed. It will thus be seenthat the above-described mechanism provides a convenient mean foradjusting or controlling the time in which the thermoplastic materialpassing between the sealing elements is subjected to the pressure andheat imparted thereto, thus materially affecting the efliciency of theseal produced.

The upper sealing roll3I is mounted on a shaft 63 journaled in uprights34 and is disposed directly above the lower roll 39. Shaft 63 isprovided adjacent the end thereof opposite the roll 3I with a spur gear64 which meshes with spur gear 35 mounted on shaft 32, thus providing adriving means for the upper roll 3|. The spur gears 35 and B4 areprovided with the same number of teeth and consequently the shaft 93 isdriven at the same speed as the shaft 32 and since the rolls 30 and 3iare of the same diameter the surface speed of the two is the same andconsequently there will be no slippage between the thermoplasticmaterial and the rolls during the sealing operation.

Since it is necessary that a variable downward pressure be applied tothe upper roll 3| in order to effectively seal the material passingbetween this roll and the lower roll 39 there is provided means foraccomplishing this result in the form of a coil compression spring 65received about a rod 59 extending upwardly through the frame ID, the rod55 having a threaded lower end 57 which receives a wing nut 98 servingto adjust the compressive effect of spring 95. The rod'GG may beprovided with a collar 89 at its lower end to prevent inadvertentremoval of the wing nut 68.

Rod 25 extends upwardly and is provided with a laterally extendingportion 73 which, as shown in Figs. 3 and 6, is pivotally received inone end of a link Ii, the opposite end of which is pivotally mounted at72 on a stud I3 secured in the upper end of one of the uprights 34 by aset screw I4. The link ll is guided by a slotted stud I5 which is alsomounted in the upright 34 by a set screw 13.

The shaft 93 supporting the upper sealing roll 31 which passes throughthe upright 34 is journale'd. therein by an anti-friction bearing 11which in turn is received in an elongated or oval aperture 13 providedin the upright 34. Directly above the bearing 11 there is provided a pin19 slidably mounted in an aperture 89 in the upright 34, the lower endof pin 19 engaging the upper surface of bearing 11 and the upper end ofpin 19 engaging the lower surface of link 1|. It will thus be seen thatthe compressive force exerted by compression spring 65 will tend to movethe rod 66 downwardly and thus pivot the link 1| in a clockwisedirection as viewed in Fig. 6 to move the pin 19 downwardly and exert adownward pressure on the bearing 11, shaft 63 and thus on the upper roll3|. Any upward pressure exerted on the roll 3| will tend to move theshaft 63 upwardly and through link 1| the rod 66 will move upwardlyagainst the action of compression spring 65. Adjustment of the wing nut68 provides a convenient means for controlling the pressure exerted bythe upper roll 3| upon the material passing between this roll and thelower roll 39 thus varying the bond secured in the seam being made atthe time.

The sealing rolls 39 and 3| are each provided with an annular recess 8|in the rear surface thereof and in these recesses there is positioned aheating element 82 having resistance wire 83 disposed therein to providethe necessary heat to efiect the seal between the surfaces of thethermoplastic material. The recesses 8| are closed by cover plates 84which cover plates are provided with spacing screws 85 threadedlyreceived therein and locked in position by lock nuts 86, screws 85serving to tightly position the heating elements 82 against the forwardface of the recess 8| in the rolls 39 and 3|. Also positioned in theplate 84 of the upper roll 3| is a thermostat 81 which may be ofconventional construction and provided with a bi-metallic element whichwill move in either direction upon a change in temperature of theheating element 82. The bimetallic strip or element 98 serves to openand close contacts which control the flow of electrical current to theheating element 82, the position at which the contacts are opened andclosed being controlled by a pin 89 extending through the thermostat andengaging the bi-metallic element 98. The position of the pin 89 andconsequently the opening and closing points of the contacts associatedwith the bi-metallic element 88 is controlled by a pivoted member 99extending through a nipple 9| to the interior of shaft 63 which ishollow. The inner end of member 99 serves to receive a rod 92 providedwith a head 93 on the outer end thereof. Rod 92 extends through shaft 63to the opposite end thereof and is connected to an adjusting member 94by a set screw 95, member 94 being threadedly received in the end ofshaft 63. Member 94 is also provided with a finger-engaging operatingknob 96 and a dial 91 which may carry indicia indicating the degree ofheat in the rolls 39 and 3|, there being a pointer 98 secured to androtating with the upper spur gear 64 whereby the dial 91 and setting ofthe thermostat 81 may be conveniently adjusted. By this means thetemperature of the rolls 39 and 3| may be adjusted to very close limitseven during operation of the machine or, in other words, while the rolls39 and 3| are rotating.

The heating elements 82 disposed in rolls 39 and 3| receive theirenergizing electrical current from slip rings 99 mounted on shaft 63 andslip rings I99.mount ed on shaft 32. Slip rings 99 substantially rightangles thereto.

are engaged by brushes 'I9I slidably mounted'in a bracket ofinsulating-material I92 which in turn is secured to a member I93 mountedonuprights 34. Brushes I9I' are urged inwardly against the slip rings 99by spring contact members I94. The slip rings I99 on the lower shaft 32are engaged by brushes I slidably mounted in bracket I92, these brushesbeing urged inwardly against the slip rings I99 by spring contactmembers I96. The conductors from slip rings 99 and I99 which areconnected to the heating elements 82 are disposed within the hollowshafts 32 and 63 but for clarity of illustration these conductors arenot shown in the drawings although they are illustrated in the circuitdiagram of Fig. 11.

Where two sheets of thermoplastic material are to be sealed together itis often desirable to provide the seam with a binding strip and for thispurpose there is provided in the machine of this invention a bindingtape supply means which maybe mounted on a shelf or bracket I91 securedto the frame I 9. The tape supply means comprises an upstanding rod I98which serves to receive and support a shaft I99 extending at Shaft I99may be conveniently secured to upstanding rod I98 by a collar II9 whichserves to threadedly receive a set screw, not shown, for clamping thesame to the rod I98. Rotatably mounted on shaft I99 and held in properposition thereon by collars III is a mandrel 2 which may be providedwith a plurality of longitudinally extending spring fingers II3, theouter diameter of mandrel II2 being slightly less than the innerdiameter of a roll of tape I I4. The spring fingers -II3 serve to firmlyengage the inner surface of the tape roll I I4 to hold the same inproper position on the mandrel and permit rotation and feeding of thetape therefrom.

Mounted adjacent the upstanding rod I98 on the bracket or shelf I91 is atape-pulling mechanism comprising a friction or drive pulley II5 mountedon a shaft III; which is journaled for rotation in an upstanding bracketII'I secured to the shelf I91 by screw-threaded fastening means or thelike I I8. Shaft I I6 extends through the cover or housing I2 and isprovided on its inner end with a bevel gear II9 which meshes with bevelgear I29 fixed on upper roll shaft 63. Thus friction drive pulley |I5will rotate with shaft 63 and the rolls 39 and 3| in synchronizedrelation thereto.

Mounted adjacent the drive pulley II5 and in parallel relation theretois a pressure pulley I2I which is rotatably mounted on anti-frictionbearings I22 carried by a stub shaft I23. Stub shaft I 23 iseccentrically supported by a shaft I24 rotatably mounted inanti-friction bearings I25 in a boss I26 extending from the inner sideof bracket II1. Shaft I24 is provided at its inner end with a collar I26which may be secured in adjusted position by a set screw or the likeI21. Also extending from collar I 26' is an actuating arm I28, thepurpose and operation of which will be presently described. Pressurepulley I2I is provided with flanges I29 on each side thereof to guideand retain the tape passing thereover in a manner which will presentlyappear. A tape guide I39 comprising a loop of wire or other suitablematerial is mounted on the bracket II1 directly above the pressurepulley I2I and serves to guide tape being fed thereto. a V

As best shown in Figs. 1 and '7, tape I3| from the roll 4 passes throughthaguidedoop I andniunder i the, pressure-pulley 'I2I. .from whichpulley it passes'over the. friction or'drive pulley I I5 and under alaterally extending xportion I32 ofthe arm I28. Movement of thelaterally extending portion I32 from the full line position to thedotted line position, as shown ,in Fig. 7, rotates the shaft I24 and dueto the eccentric arrangement of stub shaft I23 connected thereto movesthe pressure pulley I2I toward or away from the friction or drive pulleyII5, as shown in ,full and dotted lines in Fig. 7. This mechanism servesto operate and stop the tape-pullingmechanism depending upon the de--mandfor tape by the sealing machine.

The binding tape I31 is fed from the tapepulling mechanism.above-described to a tapemoistening apparatus by which a solvent isapplied to' one surface of the tape. 'The tapemoistening apparatuscomprises a receptacle I33 for receiving a suitable solvent, thisreceptacle being supported on the shelf I01. The solvent is'maintainedat a level indicated by the line I34 in a manner to be presentlydescribed. Mounted within the container I33 are partitions I35 and I35,these partitions being provided with vertically extending slots I31.Rotatably mounted within the slots. I3'Iand for vertical slidingmovement is a shaft I38 which serves to support a roller I39 the lowerportionof which is immersed in thesolvent within the container I33, theslots I3? providing a convenient means for permitting removal of theroller I39 for cleaning purposes. Also rotatably mounted on partitionsI35 and I56 insubstantially parallel .relation with the roller I35 is aguide roller I-III,

.the purpose and operation of which will presentlyappear.

The container I33 is supplied with solvent through an aperture MI inthepartition I36, this aperture communicating with a channel I 12 whichin turn communicates with a well M3. Well I43 serves to receive the neckI I I of a bottle or other suitable solvent reservoir M5, this bottlebeing supported in inverted position, as best shown in .Figs. land 8,-by a looped wire I45 or other. suitable material extending around thebottle and being supported by a collar I4? secured by aset screw or thelike I43 to a pedestal I55 mounted on the shelf I51. The bottle orreservoir iefiprovides a barometric feed for the solvent since the lowerend of neck I45 is normally disposed below the level of the solventindicated .by line I34. The bottle is supplied with a valve in the formof a washer I disposed inwardly offthe neck I of the bottle Hi5, thiswasher being of sufhcient diameter to close the neck when contacting theinner walls thereof and being supported by a rod I5I extending outwardlyof the neck I MI, there being a compression spring .I52Hsecured to thelower end of rod- I5I and to theneck I44. Thus upon removal of thebottie .I45'upwardly from the'well I53 the spring I52 acting. downwardlyon the rod I5I will .move the valve washer I50 into engagement withthesidewalls of the neck I44 and'close the'same. .This valve structure is:similar to that used in the tanks of conventional home oil stoves orranges --and operates 1 to provide a substantially constant level ofsolvent withinthe container I33.

Disposed-between the tape-moistening apparatus and thetape-puller is atape-tensioning means comprising a box-like structure I53 havingupstanding side walls I54 provided with vertical slots I55 anddownwardly curved converging upperwalls I 56 which provide a surface forengagthe full line position.

ingthe: tape I3 I FSlidably and rotatablymounted within the slots I55 isagshaft I5I which serves to. support a roller I58 of sufficient weight1130 urge the tape ISI against the curved surfaces I 56 to provide asufiicient tension in the tape between the same and the tape-moisteningmechanism. .A tape guide I59. is'securedy'to the 'boxlike structure I53by screw-threaded fastening means or the like I60 and upstanding spacedflanges ISI are provided to properly guide the tape I3I to thetensioning roller I58.

Since it is desirable thatexcess solvent be re- .moved from-the surfaceof the tape I3 I. and since the. quantitywof solvent applied.thcretozmay need to be. varied in accordance with :the character of thematerial and the thickness of the plies rto'be joined thereis provided awiper in the form of a rod I52 extending transverselyof the tape I3I androtatablymountedin'the partitions I35.and I 35. Rod I62, as best shownin Fig. 10, is ofrirregular cross section and provides a relativelysharp edge I83 and a rounded or smooth surface I54. In Fig. 10 thesharpedge I53 isshown:in full lines in engagement with the tape vI3I and therounded or smooth surface Ifit is shown in dotted lines in engagementwith the tape. The rod I52 operates to wipe excess solvent from the tapeI3Iand return this solvent to the container I33. Adjusting means for therod 52 is provided intheform of a knurled finger-engaging knob J55attached thereto, there being also provided a wing-type lock-nut'I55,.threadedly received on the rodaifiito lock the same in adjustedposition.

1 operation tape is fed from the roll II through the guideloop I38 andunder the pressure pulley IZI, the flanges- I29 serving toretain thetape I3I thereon. From pulleyI2I the tape I3I passes over the frictiondrive pulley I I5 and under the lateral extension 532 of arm I28. Fromextension I 32 the tape passes over guide I59and between flanges I SIthence under the tension roller .158 which holds the sameinengagementwith the downwardly curved surfaces I55. From here the tapepasses overthe moistening roller I39 which applies solvent thereto and beneath-theroller I48 which, as shown in-F'ig. '7,

depresses the tape downwardly to insurethat the lower surface thereofremains in contact with the surface of the roller I39 at all times. Fromroller 14s the tape passes over rod I52 at which time any excess solventon the lower surface thereof is removed and returned to the containerI33. From this point the tape I3I is supplied to a folding mechanismI65, shown in general in Fig. l, the details of which form no part ofthis invention and therefore will not be specifically described... Fromthe folding mechanism I66- the tape moves to the sealing rolls 38 and 3iand is applied to the sheets which are being fed therebetween by theconveyor belts I8. Since the friction drive pulley ii irotates insynohronism with the sealing rolls 3B and 3|, the tape I3I will be fedthereto at the same speed. However, if the tape I3I breaks or, for somereason it is not desired to utilize-the tape, release of tension thereonallowsthe lateral extension I32 of arm I28 to move from the-dotted lineposition in Fig. 7 to I This movement results 1n rotating the shaft I24and eccentrically mounted'stub shaft I23 to move the pressure pulley I2Iaway from the friction drive pulley I I5, therefore interrup'tingthefeed of the tape in that therewill not besuflicient friction between thepulley us and the tape m to pull the same from :roll. H4. Uponreapplying tension te -the tape I3I the extension I32 of arm I28 willmovefrom the full line position shown in Fig. '1 to the dotted lineposition, thus moving the pressure pulley I2I to press the tape I3Iagainst the surface of friction drive pulley II5 thereby reestablishingthe feed of the tape.

The electrical circuit of the sealing machine of this invention, asshown in Fig. 11, is supplied with electrical current through conductorsI61 and I68 which are connected to a flexible supply cord provided witha conventional male-type connector at the outer end thereof. Connectedto conductors I91 and I68 are conductors I89 which serve to supplycurrent to the lamp 28 mounted on the end of goose neck 21. Alsoconnected to conductors I81 and IE8 are conductors I19 which serve tosupply electrical current tomotor 44, the operation of this motor beingcontrolled by on and off switch I4.

Conductor I61 is connected to one contact I1I of a. normally open relayI12. Conductor I61 is also connected to one side of the coil I18 formingthe solenoid of relay I12 and which, when energized, serves to actuatethe movable contact I14 to closed position. The other contact I15 ofrelay I12 is connected through a wire I16 to one movable contact .I11 ofa double pole, double throw switch I5.

The heating element 82 in upper roll 3| is provided with electricalcurrent from the slip rings 99 mounted on shaft 83, there being one slipring I18 connected to one side of the heating element 82 through aconductor I19, the opposite side of the heating element 82 beingconnected through a wire I80 with a second slip ring I8 I. Thethermostat 81 disposed in the upper roll 9| has one contact I82connected to the wire I89 and the opposite contact I83 connected by awire I84 with the third slip ring I85. 2

The heating element 82 disposed in the lower heating roll 30 is providedwith electrical current from slip rings I00, one one side of the element82 being connected by a wire I89 with slip ring I31 and the oppositeside of the element 82 being connected by a wire I88 with the secondslip ring I89. Slip rings I18, I8I and I85 are contacted by brushes I90,I9I, and I92, respectively, while slip rings I81 and I89 are contactedby brushes I99 and I94, respectively. The second movable contact I95 ondouble pole double throwswitch I5 is connected through a wire I98 withthe brush I9I engaging slip ring I8I and with the supply conductor I68.Contact I91 of switch I5 is connected through a wire I98 with contactI99 which in turn is connected by a Wire 280 with brush I99 engagingslip ring I89. Contact 291 of switch I5 is connected through a wire 292with brush I 93 engaging slip ring I 80 and with brush I99 engaging slipring I18. No connection is made to contact 283 of the switch I5 and thiscontact plays no part in the control of the sealing machine; Brush I92in contact with slip ring I85 is connected by 'a wire 204 with the coilI13 of the relay I12. In order to prevent excessive arcing between thecontacts I82 and I83 of the thermostat 81 a .1 mid. condenser'2'85 isconnected across the brushes I9I and I92 in' contact with slip rings IBI and I85 which in turn are connected across the contacts I82 and I83of the thermostat 81. This condenser materially increases the lifev ofthe thermostat contact points.

Assuming the sealing machine of this invention to beat rest and theheating elements 82 in the rolls 30 and SI to be cold the operation ofthe electrical supply and control circuit is as follows current issuppliedthrough the conductors I61. and I68 and the light 26 may beturned on or ofl'i at will, as well as may be the drive motor 44 ,byactuation of the switch I4. Current will further flow from conductor I61throughcoil I13 or solenoid I12 to actuate the movable contact I14 thusclosing the contacts HI and I15 since the complete circuitof the coilI13 will be to conductor 204 to brush I92 engaging slip ring I throughthe power line.

Assuming the double I15 of relay I 12 through conductor I16 to movablecontact I11 of the switch I5 and through contact '20I and conductor 202to brush I engaging slip ring I18 and through conductor I19 to heating;element 82, thence through conductor I80 to slip ring I 8| and throughbrush I9I and conductor- I96 to the opposite side of the power line I68thusenergizing heating element 82 to heat thesame.

Likewise the current flowing through co'nductor 202 will flow throughbrush I93 engaging slip, ring I00 and through conductor. I86 heatingele-,

ment 82 in the lower roll 30 thence through .co'nductor I88 to slip ringI89 and brush I94'and through conductor 200, contact I99 of switch-I5and contact I95 to conductor I96 and to the op-- posite side of thepower line conductor I68. .In this condition the heating elements 82will. con-- tinue to supply heat until the temperature of.

the rolls 38 and 3| reach the point-at' -.which the thermostat 81 isset, at which time the contacts I82 and. I83 will separate thusde-energizing the coil I13 of, relay I12 and opening the contacts I1]and I 15 to interrupt'the flow of current tothe heating elements 82.

With the double pole throw switch I5 in the. regular or upper position,as shown in Fig. 11.,-

current will flow from contact us to the relay I 12 throughconductorI16to the movable con-,

tact I11 of switch I5 thence through Contact I91, conductor I98 andconductor 200 tov brushfll94i which engages slip ring I89, thencethroughfcom' ductor I88 to the heating element 82in the lower roll .30through conductor I86 to the slip ring I81 and through brush I93 andconductor 202 to'the brush I99-engaging slip ring I18 thence throughconductor I19 to heating element 82 in the upper roll 3| which point thecurrent flows through conductor I80 to slip ring I8I engaged by. brush I9| from which the current-flows through wire I96 to conductor I68forming the opposite side of the supply circuit. This position of theswitch I5 places the heating elements 82 in series, thus resulting in alower wattage consumption and consequently lower potential heat in therolls30 and 9|. As before, the temperature will be controlled by openingand closing of thethermostat 81 which controls operation of the relayI12 and thus the supply of current to the heating elements. Theelectrical supply and control system above-described is relativelysimple and. :ade-- quately controls the operation of the sealing machineof this invention. V

The operation of the sealing apparatus as a whole is believed apparentfrom the above description but briefly reviewing the sameit is as-.-sumed that the motor switch I4 isin the .onpo.-;:

pole, double throw switch: I5 to be in the high or downward position,as. shown in Fig. 11, currentwill flow from contactv sitin"and that theheating *elementcontrol switch i is in either the high or regular po-fsition depending upon the temperature required.-

Itis' further assumed that the thermostat 8 T isadjusted to the desiredtemperature. The binding strip or tape l 3! is threaded through thetapefeedingmeansand the tape-moistening means aswell. as throughthe'folding mechanism I55 and sheets of plastic or objects to be formedof a thermoplastic material arepositioned on the table-i6 with thefolded tape disposed around theedges' and with the edges in a positionto be introduced between the sealing rolls 3!] and 3|. At this timethetreadle 62-is actuated to move the controlcable 5'1 and actuate thearm 49 on the variable speed transmission Al to rotatethe rolls at thedesired speed. The extent of movementofarm 39 is controlled by aflexibl'emembersuch-as a chain 266' attached to the-arm '55 andto theframe of the machine and the arm 55 and control arm 49 is returnedto itsoriginal position upon releaseofthe treadle 62 by a sprin or othersuitable tension means '28! secured to the-arm 55 and tea bracket2fi8attached to the frame- H] of the machine. The tension spring ZD-Fmay beadjusted by a rod 2% and screwthreaded means or the like emreceivedthereon.

The work progresses through the machine and through; the sealing rolls30 and 39 by the friction therebetween-as well as by the conveyor beltsland upon completing of the seal the work is removed from the rolls andpackaged or otherwise-disposed of. Control of the speed of rotation ofthe rolls 3!! and 3| by actuation of the treadle 62- controls the timein which the sealing heat and pressure is applied to the work, thisbeing dependent upon the nature of the material as well asthe thicknessthereof.

It 'will-be seenthat-by the above invention there has been provided arelatively simple and inexpensivesealing machine which adequatelyperforms the functions for which it is intended.

It will be obvious to those skilled in the art that variouschanges maybemade in the invention without: departing fromthespirit and scopethereof: and therefore'ithe' invention is not. limitedby that which isshown in the drawings and. describedin thespecificationbut only asindicated in the appended claims.

What is claimed is:

1. Asealin machine for forming a seam between two sheets ofthermoplastic material comprising in combination a frame, awork table onsaid frame for supporting superimposed sheets to bejoined with twoadjacent edges in substantial alignment, conveyor means associated withsaid table 'for feeding said sheets longitudinally there of, spacedsubstantially parallel hollow shafts journaled-in said frameone abovetheother, a sealingroll'flxed to one end of each shaft adjacent an edge ofsaidtable, means for driving said rolls comprising a motor and avariable speed transmission, treadle means" mountedon said frame forcontrolling the output of said transmission whereby the speed ofrotation of said rolls may be infinitely varied between zero andmaximum, means on one of said rolls for driving said conveyor insynchronism-therewith, a heating element disposed in each roll, sliprings fixed on said shafts and brushes in contact therewith, conductorsconneoted to 'said heating elements. and said slip rings and extendingthrough said hollow shafts wherebyelectrical energy may be:supplied;:tosaid heating elements, a relay conted. mxanielectrical supplyi circuitfor said heating elements, an adjustable thermostat: dis posed in oneroll and connected through said with the tension in the tape fedtherefrom, means for applying solvent to one surface of said tape,

means for removin excess solvent from said tape, I

means for longitudinally folding said tape upon itself and applying thesame over the edges of said sheets to be joined whereby upon passingbetween said sealing rolls said sheets will be joined to said bindingtape under the action of heat and pressure to form a continuous sheet.

2. A sealing machine for forming a seam between two sheets ofthermoplastic material comprising in combination a frame, a work tableon said frame for supportin superimposed. sheets to be joined with twoadjacent edges in substantial alignment, spaced substantially parallelhollow shafts journaled in said frame one above the other, a sealingroll fixed to one end of each shaft adjacent an edge of said table,means for driving said rolls comprising a motor and a variable speedtransmission, treadle means mounted on said frame for controlling theoutput of said transmission whereby the speed of rotation of said rollsmay be infinitely varied between zero and maximum, a heating elementdisposed in each roll, slip rings fixed on said shafts and brushes incontact therewith, conductors connected to said heating elements andsaid slip rings and extending through said hollow shafts wherebyelectrical energy may be supplied to said heating elements, a relayconnected in the electrical supply circuit for said heating elements, anadjustable thermostat disposed in one roll and connected through saidslip rings to said relay whereby the temperature of said heatingelements may be controlled, means for adjusting said thermostat, meansfor permitting movement of one roll away from the other, adjustableyieldable means for biasing said rolls towards each other whereby thepressure applied to work therebetween may be varied, means forsupporting a supply of thermoplastic binding tape on said frame,tape-pulling means driven by said sealing roll drive means insynchronism therewith, means for rendering said tape-pulling meansoperative or inoperative in accordance with the tension in the tape fedtherefrom, means for applying solvent to one surface of said tape, meansfor removing excess solvent from said tape, means for longitudinallyfolding said tape upon itself and applying the same over the edges ofsaid sheets to be joined whereby upon passin between said sealing rollssaid sheets will be joined to said bindin tape under the action of heatand pressure to form a continuous sheet.

3. A sealing machine for forming a seam between two sheets ofthermoplastic material comprising in combination a frame, a work tableon said frame for supporting superimposed sheets to be'joined with twoadjacent edges in substantial alignment, spaced substantially parallelshafts journalednin said frame-one above the other,

a sealing-roll fixed toone end of each shaft adjacent an edge of'saidtable, means for driving said rolls comprising a motor anda variablespeed transmission, treadle means mounted on said frame for controllinthe output of said transmission whereby the speed of rotation of saidrolls may beinfinitely varied between zero and maximum, a heatingelement disposed in each roll, slip rings fixed to said'shafts andbrushes in contact therewith, conductors connected to said heatingelements and said slip rings whereby electrical energy may be suppliedto said heating elements, a relay connected in the electrical supplycircuit for said heating elements, an adjustable thermostat disposed inone roll and connected through said slip rings to said relay whereby thetemperature of said heating elements may be controlled, means foradjusting said thermostat, means for permitting movement of one rollawayfrom the other, adjustable yieldable means for biasing said rollstowards each other whereby the pressure applied to work therebetween maybe varied, means for supportin a supply of thermoplastic binding tape onsaid frame, tape-pulling means driven by said sealing roll drive meansin synchronism therewith, mean for rendering said tape-pulling meansoperative or inoperative in accordance with the tension in the tape fedtherefrom, means for applying solvent to one surface of said tape, meansfor removing excess solvent from said tape, means for longitudinallyfolding said tape upon itself and applying the same over the edges ofsaid sheets to be joined whereby upon passing between said sealin rollssaid sheets will be joined to said binding tape under the action of heatand pressure to form a continuous sheet. I

4. A sealing machine for forming a seam between two sheets ofthermoplastic materialcomprising in combination a frame, a work table onsaid frame for supporting superimposed sheets to be joined withtwoadjacent edges in substantial alignment, spaced substantially parallelshafts journaled in said frame one above the other, a sealing roll fixedto one end of each shaft, means for driving saidrolls including avariable speed transmission, means mounted on said frame for controllingthe output of said transmission whereby the speed of rotation of saidrolls may be infinitely varied between zero and maximum, a heatingelement disposed in each roll, slip rings fixed to said shafts andbrushes in contact therewith, conductors connected to said heatingelements and said slip rings whereby electrical energy may be suppliedto said heating elements, a relay connected in the electrical supplycircuit for said heating elements, an adjustable thermostat disposed inone roll and connected through said slip rings to said relay whereby thetemperature of said heating elements may be controlled, means foradjusting said thermostat, means for permitting movementof one roll awayfrom the other, adjustable yieldable means. for biasing said rollstowards each other whereby the pressure applied to work therebetween maybe varied, means for supporting a supply of thermoplastic binding tapeon said frame, tape-pulling means driven by said sealing roll drivemeans in synchronism therewith, means for rendering said tape-pullingmeans operative or inoperative inaccordance with the tension in the tapefed therefrom, means for applying-solvent to one surface of said tape,means for removing excess solvent from said tape, means forlongitudinally folding said tape tial alignment,

upon itself and applying thesameover the edges of said sheets to bejoined whereby upon passing between said sealing rolls said sheets willbe joined to said binding tape under the action of heat and pressure toforma continuous sheet.

5. A sealing machine for forming a seam be-' tween two sheets ofthermoplastic material comprising in combination a frame, a work tableon said frame for supporting superimposed sheets to be joined with twoadjacent edges in substantial alignment, spaced substantially parallelshafts journaled in said frame one above the otherya sealing roll fixedto one end of each shaft, means for driving said rolls including avariable speed transmission, means mounted on said framefor controllingthe output of said transmission whereby the'speed of rotation of saidrolls may be infinitely varied between zero and maximum, a heatingelement disposed in each roll, means for supplying electrical energy tosaid heating elements, a relay connected in the electrical sup, plycircuit for said heating elements, an adjustable thermostat disposed inone roll and connected to said relay whereby the temperature of saidheating elements may be controlled, means for adjusting said thermostat,means for permitting movement of one roll away from the other,adjustable yieldable means for biasingsaid rolls towards each otherwhereby the pressure applied to work therebetween may be varied, meansfor supporting a supply of thermoplastic binding tape on ,said frame,tape-pulling means driven by said sealing roll drive means insynchronismtherewith, means for rendering said tape-pulling meansoperative or inoperative in accordance with the tension in the tape fedtherefrom, means for applying solvent to one surface of said tape, meansfor removing excess solvent from said tape, means for longitudinallyfolding said tape upon itself and applying-the same over the edges ofsaid sheets to be joined whereby upon passing between said sealing rollssaid sheets will be joined to said binding tape under the action of heatand pressure to form a continuoussheet.

6. A sealing machine for forming a seam between two sheets ofthermoplastic material comprising in combination a frame, a work tableon said frame for supporting superimposed sheets to be joined with twoadjacent edges in substanspaced substantially parallel shafts journaledin said frame one above the other, a sealing r011 fixed toone end ofeach shaft, means for driving said rolls including a variable speedtransmission, means mounted on said frame for controlling the output ofsaid transmission whereby the speed of rotation of said rolls may beinfinitely varied between zero and maximum, a heating element disposedin each roll, means for supplying electrical energy to said heatingelements, an adjustable thermostat disposed in one roll and connected tosaid means for supplying electrical energy whereby the temperature ofsaid heating elements may be controlled, means for adjusting saidthermostat, means for permitting movement of one roll away from theother, adjustable yieldable means for biasing said rolls toward eachother whereby the pressure applied to work therebetween may be varied,means for supporting asupply of thermoplastic binding tape on saidframe, tape-pulling means driven by said sealing roll drive means insynchronism therewith, means for rendering said tape-pulllng meansoperative or inoperative in accordance with the tension in the tape fedtherefrom, means for applying. solvent to one surfacezof:said:-tape,;means for .removing:-excess solvent.- fromsaid tape,means.v for longitudinally folding said tape ;uponitself and applyingthe samebverthe edges of said, sheets to be joined wherebyuponpassingbetween said sealing rolls saidsheets will be joined to saidbinding tape under theyaction of heat and pressure to form a ;continuoussheet.

'7. -A-;sealing machineforforming a seambetween two sheets ofthermoplastic material comprising inwcombination a frame, a work tableon saidtframe for supporting superimposed sheets to be joined withetwoadjacent edges in substantial alignment, spaced substantiallyparallel shafts J'ournaled in;said frame one above the other, a sealingroll fixed to one endof eachshaft, means for:;driving said-rolls;including avariable speed transmission, means mounted on said frame forcontrolling the output of said transmission whereb'yrthe speedofrotation of said rolls-may be infinitely varied betweenzero and maximum,aheating element disposed in each roll, means for supplying electricalenergy to said heating elements, an adjustable thermostat disposed inone roll and-connected to saidmeans for supplying electrical energywhereby the temperature of said heating elements may be controlled,means for adjusting said thermostat, means for permitting movement ofone roll away from the other, adjustable yieldable means for biasingsaid rolls toward each other whereby the pressure applied to worktherebe'tween may be varied, means for'supporting a supply ofthermoplastic bindingtape on said frame, tape-pulling means driven bysaid sealing roll drive means in synchronism therewith, means forrendering said tape-pulling means operative or inoperative in accordancewith the tension in the tape fed therefrom, means forrapplying solventto one surface of said tape, means for longitudinally foldingsaid tapeupon itself and applying the same over the edges of said sheets to beJoined whereby upon passing between said sealing rolls said sheets willbe joined-to said binding tape under the action of heat and pressure toform a'continuous sheet.

8. A sealing machine for forming 'a seam between two sheets ofthermoplastic material comprising in combination a frame, a work tableon said frame for supporting superimposed sheets tobe-joined with'twoadjacent edges in substantial "alignment, spaced substantially parallelshafts journaled in said frame one above the other, a sealing roll fixedto one end of each shaft, means for driving said rolls including avariable speed transmission, means mounted on said frame for controllingthe output of said transmission'whereby the speed of rotationof saidrolls may be varied between zero and maximum, a heating element disposedin each roll, means for supplying electrical energy to said heatingelements, an adjustable thermostat disposed in one roll and connected tosaid means 7 for supplying electrical energy whereby the temperature ofsaid heating elements may be controlled, means for adjusting saidthermostat, means for permitting movement of one roll away from theother, adjustable yieldable means for biasing'said rolls towards eachother whereby the pressure applied to work therebetween may be varied,means for supporting a supply of thermoplastic binding tape on saidframe, tape pulling means driven'bysaid sealing roll drivemeans-in;synchronismtherewith, means for applying solventtonne surfaceof said tape,'means .16 for: longitudinally foldin I ,saidtape uponitself and-applying the same .over the edgesof said sheets to be joinedwhereby upon passing between said'sealing rollsesaid sheets will bejoined to said binding tape under the action of heat and pressure toform a continuous sheet. 9. A sealing machine forrforming a seam betweentwo. sheets of thermoplastiomaterial comprisingin combination a frame, awork table on said frame for supporting superimposed sheets to be joinedwith ;two adjacent edges in substantial alignment, spaced substantiallyparallel shafts journaled in said frame one above the other, asealingrollfixed to one end of :each shaft, means forriving said grollsincludinga variable speed transmission, means ,mountedon said framejforcontrolling the output of-said transmission whereby the speed ofrotation of saidrollsgmay be infinitely varied betvveensero and maximum,aeheating element disposedin each roll, means for-supplyingelectrical-energy to said heating elements, an adjustable thermostatdisposed in one roll and connectedtosaid means for supplying electricalenergy whereby the temperatureof said heating elements 1may becontrolled, means for'adjusting saidthermostat, means for permittingmovement of one roll away from the other, adjustable yieldable means forbiasing said rolls toward each other whereby the pressure applied towork therebetween may be varied, means for supporting asupply ofthermoplastic binding'tape on said frame, tape pulling means driven bysaid sealing roll drive means in synchronism therewith, means forlongitudinally folding said tape upon itself and applyingthe same overthe edges of said sheets to be joined whereby upon passing between saidsealing rolls said sheets will be joined to said bindingtape under theaction-of heat and pressure to form a continuoussheet;

10. A sealing machine as defined in claim 1 in which said tape pullingmeans comprises a friction roll driven by said sealing roll drivingmeans, a pressure roll mounted adjacent said friction roll for movementtoward and away therefrom, a stub shaft rotatably receiving saidpressure roll, a shaft eocentrically secured to said stub shaft androtatably mounted on said frame, an arm secured to said shaft and havinga lateral extension disposed in the path of movement of tape trainedover said friction roll whereby tape under tension passing'under saidextension will rotate said shaft and move said pressure roll towardssaidfriction roll to cause drivingengagement between said friction-roll andsaid tape to feed the same and uponrelease of tension in said tape saidpressure roll will move away from said friction roll to interrupt saiddriving engagement.

11. A sealing machine as definedin claim 7 in which said tape pullingmeans comprises a friction roll driven by said sealingroll drivingmeans, a pressure roll mounted adjacent said friction roll for movementtoward and away therefrom, a stub shaftrotatably.receiving.said'pressureroll, a shaft ,eccentrically secured tosaid stub shaft and-rotatably,mounted on said frame, anarmsecured to said shaft and having a lateralextension disposedpin the path ofmovement of tape, trained ,over saidfriction roll wherebytape under tension passing underjsaid extensionwill rotate said shaft andmove said pressure roll towards said frictionroll to cause driving engagement between said friction-roll and saidtape to feed thesame' and uponreleaseof-tension in said tape, saidpressure roll will move away from said friction roll o interrupt-saiddriving I engagement; V

12. A sealing machine as defined *inclaim"7 in which said tape pullingmeans comprises a friction roll -driven ;by;'-said -sealing roll drivingmeans, a pressure roll mounted adjacent said friction roll formovementtoward and away therefrom, eccentric means" for mounting saidpressure'roll on said frame, an-arm secur'edto said eccentric means andhaving a lateral extension disposed in the path of movement oftapetrained overv said friction roll whereby tape under tension passingunder said extension will move said pressure roll towardssaidfr tionroll toipause driving engagement between s id'friction-roll and drivingengagement. l

13.'A sealing machine as" defined inclarmfl in which said tape pullingmeans comprises a friction roll driven by said sealing roll drivingmeans, a pressure roll mounted adjacent said friction roll for movementtoward and away therefrom, means disposed in the path of movement oftape trained over said friction roll and connected to said pressure rollfor moving the same toward and away from said friction roll whereby tapeunder tension passing under said means will move towards said frictionroll to cause driving engagement between said friction roll and saidtape to feed the same and upon release of tension in said tape saidpressure roll will move away from said friction roll to interrupt saiddriving engagement.

14. A sealing machine as defined in claim 7 in which said solventapplying means comprises an open top container, spaced substantiallyparallel partitions in said container, opposed vertical slots in saidpartitions, a solvent applying roller having a shaft removably receivedin said slots with the lower portion of said roller immersed in solventin said container and with the upper portion of said roller above thelevel of the solvent, a second roller substantially parallel to saidapplying roller and rotatably mounted on said partitions with the lowerportion of said second roller below the upper portion of said applyingroller whereby tape passing over said applying roller and under saidsecond roller will be held in firm engagement with said applying rollerto receive solvent therefrom, a well adjacent said container, 2. channelcommunicating with said container and said well, a solvent reservoirhaving a filling and discharge opening formed by a neck, a valvedisposed in said neck for closing the same, resilient means for biasingsaid valve to closed position and means to open said Valve, saidreservoir being disposed in inverted position with said neck in saidwell and with said valve open whereby a barometric feed is provided tomaintain a substantially constant level of solvent insaid container.

l5.-A sealing machine a defined in claim 7 in which said solventapplying means comprises a container, spaced partitions in saidcontainer, opposed vertical slots in said partitions, a solvent applyingroller having a shaft removably received in said slots with the lowerportion of said roller immersed in solvent in said container and withthe upper portion of said roller above the level of the solvent, asecond roller rotatably mounted on said partitions with the lowerportion of said second roller below the upper portion pos'ition 'with'said neck in said well and with said valve'open whereby a barometricfeed is provided to maintain a substantially constant level of solventin said container, 7 16. A'sealing'machine as defined in claim 7 whichsa'idsolvent applying means comprises 'a cemamer, a solvent applyingroller rotatably ted in said container with the'lower por- {t1on"ofsaid' roller'immersed insolvent in'said container and with {the upper'portion' of "said roller above the level of the solvent, a secondroller rotatably mounted in said container with the lower portion ofsaid second roller below the upper portion of said applying rollerwhereby tape passing over said applying roller and under said secondroller will be held in firm engagement with said applying roller toreceive solvent therefrom, a well adjacent said container, a channelcommunicating with said container and said well, a solvent reservoirhaving a filling and discharge opening formed by a neck, a valvedisposed in said neck for closing the same, resilient means for biasingsaid valve to closed position and 7 means to open said valve, saidreservoir being disposed in inverted position with said neck inv saidwell and with said valve open whereby a barometric feed is provided tomaintain a substantially constant level of solvent in said container. V

17. A sealing machine as defined in claim 7 in'which said solventapplying means comprises a container, a solvent applying rollerrotatably mounted in said container with the lower portion of saidroller immersed in solvent in said container and with the upper portionof said roller above the level of the solvent, means to maintain tape infirm engagement with said applying roller to receive solvent'therefrom,a well adjacent said container, a channel communicating with saidcontainer and said well,,a solvent reservoir having a filling anddischarge opening formed by a neck, a valve disposed in said neck forclosing the same, resilient means for biasing said valve to closedposition and means to open said valve, said reservoir being disposed ininverted position with said neck in said well and with said valve openwhereby a barometric feed is provided to maintain a substantiallyconstant level of solvent in said container.

w 18. A sealing machine as defined in claim '7 in which said solventapplying means comprisessaid well whereby a barometric feed is providedto maintain a substantially constant level of solvent; in saidcontainer.- I 7 :194A sealing machine as defined. in claim '7 in whichsaid solvent applying meansv comprises a container, a solvent applyingroller rotatably mounted in said container with the lower portion ofsaid roller, immersed in solvent in said container and. with the upper.portion of said roller above the level of the solvent, means to maintaintape in firm engagement withsaid applying roller to, receivesolvent-therefrom and meansto maintain substantially constant level ofsolvent in saidcontainer.-

20. A sealing machine as defined. in claim 6 inwhich the means forremoving excess solvent from the tape comprises a rod of irregular crosssection disposed-in the path of movement of tape of saidsolventrapplying means, a relatively sharp edge onone side of'said rodand a smooth surface on the opposite side and'means to adjust said rod.to selectively engage said sharp edge or said smooth surfacexwithsaidtapeto vary the wiping action whereby excess solvent is removed fromsaidtapa.

JAMESM.

JOHN JOSEPH GREVICH.

REFERENCES CITED a The following references are of record: in'the fileof this. patent:

UNITED STATES lATENTS I Date Number -Name 1,115,828 Johnston "Nov. 3;1914 1,195,310 v 7 White et a1. Aug. 22, 1916 1,638,664 Greenfield Aug.9, 1927 2,003,337 Brady et 1 June 4,1935 2,126,908 Moore Aug..16, 19382,244,282 Bergstein June 3, 1941 2,495,680 Andrews Jan. 21, 1950

1. A SEALING MACHINE FOR FORMING A SEAM BETWEEN TWO SHEETS OFTHERMOPLASTIC MATERIAL COMPRISING IN COMBINATION A FRAME, A WORK TABLEON SAID FRAME FOR SUPPORTING SUPERIMPOSED SHEETS TO BE JOINED WITH TWOADJACENT EDGES IN SUBSTANTIAL ALIGNMENT, CONVEYOR MEANS ASSOCIATED WITHSAID TABLE FOR FEEDING SAID SHEETS LONGITUDINALLY THEREOF, SPACEDSUBSTANTIALLY PARALLEL HOLLOW SHAFTS JOURNALED IN SAID FRAME ONE ABOVETHE OTHER, A SEALING ROLL FIXED TO ONE END OF EACH SHAFT ADJACENT ANEDGE OF SAID TABLE, MEANS FOR DRIVING SAID ROLLS COMPRISING A MOTOR ANDA VARIABLE SPEED TRANSMISSION, TREADLE MEANS MOUNTED ON SAID FRAME FORCONTROLLING THE OUTPUT OF SAID STRANSMISSION WHEREBY THE SPEED OFROTATION OF SAID ROLLS MAY BE INFINITELY VAIRED BETWEEN ZERO ANDMAXIMUM, MEANS ON ONE OF SAID ROLLS FOR DRIVING SAID CONVEYOR INSYNCHRONISM THEREWITH, A HEATING ELEMENT DISPOSED IN EACH ROLL, SLIPRINGS FIXED ON SAID SHAFTS AND BRUSHES IN CONTACT THEREWITH, CONDUCTORSCONNECTED TO SAID HEATING ELEMENTS AND SAID SLIP RINGS AND EXTENDINGTHROUGH SAID HOLLOW SHAFTS WHEREBY ELECTRICAL ENERGY MAY BE SUPPLIED TOSAID HEATING ELEMENTS, A RELAY CONNECTED IN AN ELECTRICAL SUPPLY CIRCUITFOR SAID HEATING ELEMENTS, AN ADJUSTABLE THERMOSTAT DISPOSED IN ONE ROLLAND CONNECTED THROUGH SAID SLIP RINGS TO SAID RELAY WHEREBY THETEMPERATURE OF SAID HEATING ELEMENTS MAY BE CONTROLLED, MEANS FORADJUSTING SAID THERMOSTAT, MEANS FOR PERMITTING MOVEMENT OF ONE ROLLAWAY FROM THE OTHER, ADJUSTABLE YIELDABLE MEANS FOR BIASING SAID ROLLSTOWARDS EACH OTHER WHEREBY THE PRESSURE APPLIED TO WORK THEREBETWEEN MAYBE VARIED, MEANS FOR SUPPORTING A SUPPLY OF THERMOPLASTIC BINDING TAPEON SAID FRAME, TAPE-PULLING MEANS DRIVEN BY SAID SEALING ROLL DRIVEMEANS IN SYNCHRONISM THEREWITH, MEANS FOR RENDERING SAID TAPE-PULLINGMEANS OPERATIVE OR INOPERATIVE IN ACCORDANCE WITH THE TENSION IN THETAPE FED THEREFROM, MEANS FOR APPLYING SOLVENT TO ONE SURFACE OF SAIDTAPE, MEANS FOR REMOVING EXCESS SOLVENT FROM SAID TAPE, MEANS FORLONGITUDINALLY FOLDING SAID TAPE UPON ITSELF AND APPLYING THE SAME OVERTHE EDGES OF SAID SHEETS TO BE JOINED WHEREBY UPON PASSING BETWEEN SAIDSEALING ROLLS SAID SHEETS WILL BE JOINED TO SAID BINDING TAPE UNDER THEACTION OF HEAT AND PRESSURE TO FORM A CONTINUOUS SHEET.